For the next two months, the California Department of Fish and Wildlife will be releasing 200,000 hatchery-raised Chinook Salmon into Battle Creek near the Sacramento River in California.
During the 1930s, dams were built for power generation and water storage, which blocked the winter-run Chinook from cooler upstream waterways. Trapped by the warm water, the Chinook population dropped from nearly a million to just a few thousand, making the fish one of eight marine species most at risk for extinction.
The project to restore 48 miles of salmon habitat began in 1999. California's wildlife department, in collaboration with the U.S. Fish and Wildlife Service, the Bureau of Reclamation, NOAA Fisheries and Pacific Gas and Electric Co., has spent $100 million so far building fish ladders and screens and removing dams and weirs that block migration on the creek.
The ongoing restoration project has removed one dam and is set to remove four more dams. The Associated Press says a proposal is being considered by the Federal Energy Regulatory Commission to remove a series of dams farther north in the Klamath River.
For more, here is the San Francisco Chronicle's Science article.